Removing a 2003-2005 Honda Civic Hybrid IMA battery and installing a Bypass adaptor.


It takes first-timers about 30 minutes to remove the battery. With practice, you can replace the battery in 15 minutes.

Tools required: 10mm socket, 12mm socket, 8" or longer extension, Torx-T30 star bit, voltmeter

Opening the lid
O1. Open the hood. HCH I
O2. Disconnect the 12V battery. HCH I
O3. You will need to remove the rear seat. HCH I
O4. Locate and remove the 10mm bolt at the center passenger's left hip. 2004-2005 Civic's have a second bolt at the right hip. HCH I
O5. Pull up on the front edge of the lower cushion. Remove the cushion from the car. HCH I
O6. Remove the two bolts at the lower corners of the seatback. HCH I
O7. Slide the seatback toward the ceiling and remove it from the car. HCH I
O8. Open the hatch and turn off the switch. Reinstall the red safety guard. HCH I
O9. Remove the Torx T-30 bolts. HCH I
O10. Remove the little black clip next to the switch. HCH I
O11. Remove the cover. HCH I

Removing the battery
R1. Test the voltage at the cables marked + and -. If you read more than 12V, put the cover back on and contact us. HCH I
R2. Disconnect the + and - cables and these three connectors. HCH I
R3. Unplug this cable and unclip it. HCH I
R4. Unscrew this bolt to remove this grounding wire. HCH I
R5. This orange plug cannot be opened until you release it from its' clip. HCH I
R6. It slides off this clip. HCH I
R7. Pull up on the little tab... HCH I
R8. ... and slide it sideways. Once it is off the metal clip, squeeze the button to release. HCH I
R9. Remove the four 12mm bolts. HCH I
R10. Remove this 10mm bolt and clip. HCH I
R11. Pull out the battery by the straps. HCH I

Installing the Bypass adaptor
B1. Install the bypass board where the battery was. HCH I
B2. Connect the high-voltage leads. HCH I
B3. Connect this plug. HCH I
B4. Find these connectors on the bottom of the computer. HCH I
B5. Unplug this plug. HCH I
B6. When done, it should look like this. HCH I

Closing the cover
C1. Put the cover back on. Make sure to get the tabs in the holes when reinstalling the cover. HCH I
C2. Install the Torx T-30 bolts. The cover must form an airtight seal, so all the bolts must be installed. HCH I
C3. There is no need to install the little black clip next to the switch - there is no switch.
C4. Close the hatch in the cover. HCH I
C5. Slide the seatbelt tongues all the way up to the top of the belts. Reinstall the seatback. You may have to press toward the back of the car to engage the three hooks into their holes. Then slide the seatback down toward the floor until it is in place.
C6. Install the two bolts at the lower corners of the seatback. HCH I
C7. Install the lower cushion taking care to get the seat belt buckles above the seat. Press down until they click to lock them in place. HCH I
C8. Reinstall the one or two (depends on year) 10mm bolts that hold the seat cushion in place. HCH I
C9. Start your car (you may have to hold the key for a few seconds) and pay attention to the little red battery light on the dashboard. It should go out when you raise the idle to 1500 or more. If not, turn off the car wait a few seconds and try again. If it still doesn't go out, contact us.
C10. At idle, your car does not produce enough power to charge your 12V battery. There is a reserve, so you just need to avoid leaving it at idle for a long time. If you are stuck at a train crossing, turn the car off.
Above 3800 rpm, your IMA system will overload and shut down for 30-45 seconds (and the light will come on). This happens at about 75mph. Try to avoid this.

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